Ecoregions of
North Dakota
and
South Dakota

17. Middle Rockies

17a. Black Hills Foothills

Level IV Ecoregion

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North Dakota Ecoregions

South Dakota Ecoregions

17a. Black Hills Foothills

17b. Black Hills Plateau

17c. Black Hills Core Highlands

The Middle Rockies ecoregion is characterized by individual mountain ranges of mixed geology interspersed with high elevation, grassy parkland. The Black Hills are an outlier of the Middle Rockies and share with them a montane climate, hydrography, and land use pattern. Ranching and woodland grazing, logging, recreation, and mining are common.

Extensive landscape alteration, surface and ground water contamination, and the high cost of reclamation make surface mining a controversial issue in the Black Hills of South Dakota.

Two contrasting landscapes, the Hogback Ridge and the Red Valley (or Racetrack), compose the Black Hills Foothills ecoregion. Each forms a concentric ring around the mountainous core of the Black Hills (ecoregions l7b and 17c). Ponderosa pine cover the crest of the hogback and the interior foothills. Buffalo, antelope, deer, and elk still graze the Red Valley grasslands in Custer State Park.

Physiography

Area (square miles): 900
Elevation/Local Relief (feet): 3300-4900/450-1100
Unglaciated. A ring of foothills surrounding the Black Hills' mountainous core. The Dakota Hogback separates the foothills from the plains. The Red Valley (Racetrack) inside the hogback encircles the Black Hills dome.

Geology

Surficial Material and Bedrock
Mesozoic sandstone and shale. The Hogback is composed of Lakota Sandstone, Fall River Sandstone, Fuson Shale, and Minnewasta Limestone. The Red Valley is composed of the Spearfish Formation, a red sandy shale.

Soil

Order (Great Groups)
Entisols (Torriorthents), Mollisols (Argiustolls, Haplustolls)
Common Soil Series
Butche, Canon, Enning, Nevee, Spearfish, Grummit, Tilford, Vale, Rekop
Temperature/Moisture Regimes
Mesic/Ustic

Climate

Precipitation - Mean annual (inches)
15-17
Frost Free - Mean annual (days)
110-140
Mean Temp. - Jan. min/max; July min/max, (°F)
10/36;57/86

Potential Natural Vegetation

Ponderosa pine woodlands with grass understory of little bluestem, grama grasses, and leadplant. Some burr oak in the north and Rocky Mountain juniper in the south.

Land Use and Land Cover

Cattle grazing, ranching. Suburban development in the eastern Black Hills. Ponderosa pine savannah.

Ecoregions of North Dakota and South Dakota

Ecoregions of
North Dakota
and
South Dakota